EFFECT OF PEA AND BOVINE TRYPSIN-INHIBITORS ON WILD-TYPE AND MODIFIEDTRYPSINS

In order to modify the catalytic properties of trypsin, lysine-188 (S1 ) of the substrate binding pocket was substituted by an aromatic amino acid residue (Phe, Tyr, Trp) or by a histidyl residue, Two other muta nts were obtained by displacement or elimination of the negative charg e of aspartic acid-189 (K188D/D189K and G187W/K188F/D189Y, respectivel y), The high affinity inhibitors, like PSTI II and BPTI, behaved as sp ecific substrates of the trypsin and its mutants, Their inhibiting eff ect toward modified trypsins was studied, The bovine inhibitor had a h igher affinity for all tested enzymes than pea inhibitor, The inhibiti on constants differed according to the mutations on the protease, (C) 1998 Federation of European Biochemical Societies.